The Lötschental tree-growth monitoring transect
In order to further understand and perhaps predict the effects of the projected temperature increase in forest ecosystems, the Dendrosciences group of the WSL is monitoring forest growth along both the south and north facing slopes of the Lötschental valley. The Lötschental monitoring transect is an ensemble of 9 tree-growth monitoring sites distributed along an elevational gradient from 800 to 2200 m. a.s.l. The setting was installed in fall 2006 and includes infrastructure to investigate continuous stem growth of mature Picea abies and Larix decidua trees grown under natural conditions. The originality of the setting relies on long-term monitoring of xylogenesis (wood formation) by means of weekly stem tissue sampling, in parallel with sub-hourly measurements of radial growth, sap flow, air and soil temperature, relative humidity, soil water content, soil matrix potential, and solar radiation at each site. These data have occasionally been complemented with additional measurements to characterize isotope signals in soil and tree compartments, tree phenology, the dynamics of non-structural carbohydrates in the cambium, trees’ genomic DNA, and tree-ring width and wood anatomy.